It is customary at present to use packages of non-returnable character for a large number of goods, and among them for liquid goods such as milk and similar dairy products, fruit juices, mineral water etc. The demand made on these consumer packages is that they should be inexpensive, easy to manufacture, distribute and handle and, not least, easy to open so that the contents can be made accessible in a convenient manner if required. In certain cases it is desirable also that it should be possible to reclose the package in a simple and effective manner once it has been opened.
A large group of these non-returnable packages, e.g. milk and fruit juice, consists of a rigid carrier layer of paper or cardboard which on at least one side has a coating of a plastic material which provides the package with the required liquid tightness and other necessary barrier properties, e.g. gas-tightness, and at the same time makes possible tight and durable sealing joints, in that combined layers of plastic material are heated and at the same time pressed against one another so that a fusing together of the combined plastic layers is obtained. Since most packages of this type during handling can come into contact with a moist environment it is customary, moreover, for the outsides of the packages also to have a plastic layer which prevents moisture from penetrating into the fibrous base layer which, if it became moist, would lose its mechanical rigidity, causing the package to feel soft and unmanageable.
Non-returnable packages of the abovementioned type can be manufactured today in high-capacity packing machines, where the contents are treated at the same time in a hygienic manner, and with the help of which even previously sterilized contents can be packaged under aseptic conditions in such a manner that the contents retain their sterility in the closed package during a very long period.
A well-known packing container for liquid foodstuffs contents of the type described in the introduction is the parallelepipedic container of the Tetra Brik type (registered trade mark) which customarily is manufactured from plastic-coated paper or similar packing laminate which through conventional folding and sealing operations in a packing machine of known type is formed, filled and closed so as to form finished parallelepipedic containers. Such a container often has a prepared emptying opening in the form of a hole punched out in the top side of the packing container, preferably at a corner edge, which is covered on the outside by a tear-off cover strip sealed to the package wall. The container is opened in that the strip covering it in this manner is pulled upwards and backwards so as to expose the said emptying opening.
The known packing container described certainly has a number of important advantages both from a manufacturing aspect as well as from a point of view of the user. It is simple, inexpensive and easy to manufacture in rapidly producing packing machines and also easy to distribute and to store. Moreover the container is easily openable and allows a flow of the contents in a well-defined jet. One disadvantage of the known container, however, is that it still lacks the reclosability desired from the side of the consumer which means that the emptying opening once exposed should be capable of being closed again and thus present the possibility of a "safe" storage of the contents between different pouring events.